This invention relates to a means for biological control of certain soil borne plant pathogens. Biological control is defined as pathogen control by use of a second organism. The mechanisms of biological control are quite diverse. In some instances the control is caused by production of certain chemicals by the biological organism, with the chemicals being inhibitory. In other instances, there is competition for space with the control organism occupying space, and consuming nutrients which inhibit the organism to be controlled. In further instances it may be nothing more than competition for chemical nutrients. In any event, the concept of biological control when used herein is as defined in this paragraph.
The biological control mechanism of this invention is especially designed for control of seed corn rot and corn seedling blight. It is possible that the control method of the present invention may be used for certain other plants which suffer from similar diseases caused by high moisture content in the growing media at planting time. Thus, the invention is not limited to control of corn seed rot and seedling blight, but instead is a method of controlling any types of "damping off" or "root rot" that crops such as corn, alfalfa, soybeans, etc. are known to have.
In the typical progress of corn seed rot, and seedling blight the symptoms occur early in the spring soon after planting or seed germination in a disease conducive environment. Often the seedling will be destroyed, the leaves yellow and wilt, the roots rot and fail to properly develop, and the plant is significantly impaired. It may even die. This disease is especially common when there is not only high moisture during spring planting season, but also colder temperatures.
Currently, the best known methods for treatment are chemical treatment with fungicides such as Captan. However, because of recent environmental concerns it is especially desirable to eliminate the use of potentially environmentally hazardous fungicides, such as Captan.
There is, therefore, a continuing high level of interest in developing other means for treating bacteria and fungi known to cause corn seed rot and seedling blight, especially those caused by Pythium Spp. and Fusarium graminearum. These are perhaps two of the most common species causing corn seed rot and seedling blight.
It is a primary objective of the present invention to provide a method of biological control of corn seed rot and seedling blight.
Another objective of the present invention is to provide a treating composition of inoculum for control of corn seed rot and seedling blight, which comprises a protection effective amount of a bacteria which produces bioemulsifiers and/or biosurfactants. It is selected from the group consisting of strains 6519E01, 6133D02, 6109D01 and their respective genetic equivalents, combined with a satisfactory carrier.
Another objective of the present invention is to provide a method of biological control which comprises placing the treating composition on the seed, or adjacent the seed in a growing medium, to protect said seed during its critical time periods just prior to and just after germination. Protection is provided from hazards of blight caused by Pythium Spp. and Fusarium graminearum, etc.
The method and means of accomplishing the objectives of the present invention will become apparent from the detailed description which will follow hereinafter.